/**
 * @User: vitobo
 * @Date: 2024-06-20
 * @Description: 双向链表的实现
 */

public class MyLinkedList {

    static class ListNode{
        public int val;
        public ListNode prev;
        public ListNode next;

        public ListNode(int val){
            this.val = val;
        }
    }

    public ListNode head; //标记双向链表的头部
    public ListNode tail; //标记双向链表的尾部

    // 打印双向链表中的 每个节点
    public void display(){
        ListNode cur = this.head;
        while(cur != null){
            System.out.print(cur.val + " ");
            cur = cur.next;
        }
        System.out.println();
    }

    // 得到双向链表的长度
    public int size(){
        ListNode cur = this.head;
        int count = 0;
        while(cur != null){
            count++;
            cur = cur.next;
        }
        return count;
    }

    // 查找是否包含关键字key是否在链表当中
    public boolean contains(int key){
        ListNode cur = this.head;
        while (cur != null){
            if(cur.val == key){
                return true;
            }
            cur = cur.next;
        }
        return false;
    }

    // 头插
    public void addFirst(int data){
        ListNode node = new ListNode(data);

        if(this.head == null ){
            this.head = node;
            this.tail = node;
        }else{
            node.next = this.head;
            this.head.prev = node;
            this.head = node;
        }
    }

    // 尾插
    public void addLast(int data){
        ListNode node = new ListNode(data);
        if(this.head == null ){
            this.head = node;
            this.tail = node;
        }else{
            this.tail.next = node;
            node.prev = this.tail;
            this.tail = node;
        }
    }

    // 任意位置插入,第一个节点为0号下标
    public void addIndex(int index, int data){
        ListNode node = new ListNode(data);
        // 1.判断Index位置的合法性
        if(index < 0 || index > size()){
            throw  new IndexWrongFullException("Index位置不合法! ");
        }
        // 2.判断特殊位置,头插和 尾插
        if(index == 0){
            addFirst(data);
            return;
        }
        if(index == size()){
            addLast(data);
            return;
        }
        // 3.找到index位置节点的地址
        ListNode cur = findIndexListNode(index);

        // 4.修改4个指向
        node.next = cur;
        node.prev = cur.prev;
        cur.prev.next = node;
        cur.prev = node;

    }

    private ListNode findIndexListNode(int index){
        ListNode cur = this.head;
        while(index != 0){
            cur = cur.next;
            index--;
        }
        return cur;
    }

    // * 删除第一次出现为key的关键字
    public void remove(int key){
        ListNode cur = this.head;
        while(cur != null){
            if(cur.val == key){
                if(cur == head){
                    head = head.next;
                    if(this.head != null){
                        head.prev = null;
                    }else {
                        this.tail = null;
                    }
                }else{
                    cur.prev.next = cur.next;
                    if(cur.next != null){
                        cur.next.prev = cur.prev;
                    }else {
                        this.tail = cur.prev;
                    }
                }
                return;
            }
            cur = cur.next;
        }
    }

    // 删除所有值为key的元素
    public void removeAllKey(int key){
        ListNode cur = this.head;
        while(cur != null){
            if(cur.val == key){
                if(cur == head){
                    head = head.next;
                    if(this.head != null){
                        head.prev = null;
                    }else {
                        this.tail = null;
                    }
                }else{
                    cur.prev.next = cur.next;
                    if(cur.next != null){
                        cur.next.prev = cur.prev;
                    }else {
                        this.tail = cur.prev;
                    }
                }
            }
            cur = cur.next;
        }
    }

    // 清空双向链表
    public void clear(){
        ListNode cur = this.head;
        while(cur != null){
            ListNode curNext = cur.next;
            cur.prev = null;
            cur.next = null;
            cur = curNext;
        }
        this.head = null;
        this.tail = null;
    }

}
